Seems like a start to the idea we discussed in Dallas about using cgroups to group together tasks with similar wakeup characteristics.
Thanks Daniel.
/Amit
----- Forwarded message from Daniel Lezcano daniel.lezcano@free.fr -----
Date: Wed, 02 Feb 2011 22:01:48 +0100 From: Daniel Lezcano daniel.lezcano@free.fr To: amit Kucheria amit.kucheria@linaro.org Subject: Fwd: [PATCH, v3 2/2] cgroups: introduce timer slack subsystem User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101208 Thunderbird/3.1.7
Hi Amit,
I supposed this patch may interest you ;)
Cheers -- Daniel
-------- Original Message -------- Subject: [PATCH, v3 2/2] cgroups: introduce timer slack subsystem Date: Wed, 2 Feb 2011 22:47:36 +0200 From: Kirill A. Shutsemov kirill@shutemov.name To: Paul Menage menage@google.com, Li Zefan lizf@cn.fujitsu.com CC: jacob.jun.pan@linux.intel.com, containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Arjan van de Ven arjan@linux.intel.com
From: Kirill A. Shutemovkirill@shutemov.name
Provides a way of tasks grouping by timer slack value. Introduces per cgroup max and min timer slack value. When a task attaches to a cgroup, its timer slack value adjusts (if needed) to fit min-max range.
It also provides a way to set timer slack value for all tasks in the cgroup at once.
This functionality is useful in mobile devices where certain background apps are attached to a cgroup and minimum wakeups are desired.
Signed-off-by: Kirill A. Shutemovkirill@shutemov.name Idea-by: Jacob Panjacob.jun.pan@linux.intel.com --- include/linux/cgroup_subsys.h | 6 + include/linux/init_task.h | 4 +- init/Kconfig | 10 ++ kernel/Makefile | 1 + kernel/cgroup_timer_slack.c | 242 +++++++++++++++++++++++++++++++++++++++++ kernel/sys.c | 24 +++- 6 files changed, 280 insertions(+), 7 deletions(-) create mode 100644 kernel/cgroup_timer_slack.c
diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h index ccefff0..e399228 100644 --- a/include/linux/cgroup_subsys.h +++ b/include/linux/cgroup_subsys.h @@ -66,3 +66,9 @@ SUBSYS(blkio) #endif
/* */ + +#ifdef CONFIG_CGROUP_TIMER_SLACK +SUBSYS(timer_slack) +#endif + +/* */ diff --git a/include/linux/init_task.h b/include/linux/init_task.h index caa151f..48eca8f 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -124,6 +124,8 @@ extern struct cred init_cred; # define INIT_PERF_EVENTS(tsk) #endif
+#define TIMER_SLACK_NS_DEFAULT 50000 + /* * INIT_TASK is used to set up the first task table, touch at * your own risk!. Base=0, limit=0x1fffff (=2MB) @@ -177,7 +179,7 @@ extern struct cred init_cred; .cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \ .fs_excl = ATOMIC_INIT(0), \ .pi_lock = __RAW_SPIN_LOCK_UNLOCKED(tsk.pi_lock), \ - .timer_slack_ns = 50000, /* 50 usec default slack */ \ + .timer_slack_ns = TIMER_SLACK_NS_DEFAULT, \ .pids = { \ [PIDTYPE_PID] = INIT_PID_LINK(PIDTYPE_PID), \ [PIDTYPE_PGID] = INIT_PID_LINK(PIDTYPE_PGID), \ diff --git a/init/Kconfig b/init/Kconfig index be788c0..f21b4ce 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -596,6 +596,16 @@ config CGROUP_FREEZER Provides a way to freeze and unfreeze all tasks in a cgroup.
+config CGROUP_TIMER_SLACK + tristate "Timer slack cgroup subsystem" + help + Provides a way of tasks grouping by timer slack value. + Introduces per cgroup timer slack value which will override + the default timer slack value once a task is attached to a + cgroup. + It's useful in mobile devices where certain background apps + are attached to a cgroup and minimum wakeups are desired. + config CGROUP_DEVICE bool "Device controller for cgroups" help diff --git a/kernel/Makefile b/kernel/Makefile index 353d3fe..0b60239 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -61,6 +61,7 @@ obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o obj-$(CONFIG_COMPAT) += compat.o obj-$(CONFIG_CGROUPS) += cgroup.o obj-$(CONFIG_CGROUP_FREEZER) += cgroup_freezer.o +obj-$(CONFIG_CGROUP_TIMER_SLACK) += cgroup_timer_slack.o obj-$(CONFIG_CPUSETS) += cpuset.o obj-$(CONFIG_CGROUP_NS) += ns_cgroup.o obj-$(CONFIG_UTS_NS) += utsname.o diff --git a/kernel/cgroup_timer_slack.c b/kernel/cgroup_timer_slack.c new file mode 100644 index 0000000..a343a50 --- /dev/null +++ b/kernel/cgroup_timer_slack.c @@ -0,0 +1,242 @@ +/* + * cgroup_timer_slack.c - control group timer slack subsystem + * + * Copyright Nokia Corparation, 2011 + * Author: Kirill A. Shutemov + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ +#include<linux/cgroup.h> +#include<linux/init_task.h> +#include<linux/module.h> +#include<linux/slab.h> + +struct cgroup_subsys timer_slack_subsys; +struct timer_slack_cgroup { + struct cgroup_subsys_state css; + unsigned long min_slack_ns; + unsigned long max_slack_ns; +}; + +enum { + TIMER_SLACK_MIN, + TIMER_SLACK_MAX, +}; + +int dummy_timer_slack_check(struct task_struct *task, unsigned long slack_ns); +extern int (*timer_slack_check)(struct task_struct *task, + unsigned long slack_ns); + +static struct timer_slack_cgroup *cgroup_to_tslack_cgroup(struct cgroup *cgroup) +{ + struct cgroup_subsys_state *css; + + css = cgroup_subsys_state(cgroup, timer_slack_subsys.subsys_id); + return container_of(css, struct timer_slack_cgroup, css); +} + +static int cgroup_timer_slack_check(struct task_struct *task, + unsigned long slack_ns) +{ + struct cgroup_subsys_state *css; + struct timer_slack_cgroup *tslack_cgroup; + + css = task_subsys_state(task, timer_slack_subsys.subsys_id); + tslack_cgroup = container_of(css, struct timer_slack_cgroup, css); + + if (slack_ns< tslack_cgroup->min_slack_ns) + return -EPERM; + if (slack_ns> tslack_cgroup->max_slack_ns) + return -EPERM; + return 0; +} + +static struct cgroup_subsys_state * +tslack_cgroup_create(struct cgroup_subsys *subsys, struct cgroup *cgroup) +{ + struct timer_slack_cgroup *tslack_cgroup; + + tslack_cgroup = kmalloc(sizeof(*tslack_cgroup), GFP_KERNEL); + if (!tslack_cgroup) + return ERR_PTR(-ENOMEM); + + if (cgroup->parent) { + struct timer_slack_cgroup *parent; + parent = cgroup_to_tslack_cgroup(cgroup->parent); + tslack_cgroup->min_slack_ns = parent->min_slack_ns; + tslack_cgroup->max_slack_ns = parent->max_slack_ns; + } else { + tslack_cgroup->min_slack_ns = 0UL; + tslack_cgroup->max_slack_ns = ULONG_MAX; + } + + return&tslack_cgroup->css; +} + +static void tslack_cgroup_destroy(struct cgroup_subsys *subsys, + struct cgroup *cgroup) +{ + kfree(cgroup_to_tslack_cgroup(cgroup)); +} + +/* + * Adjust ->timer_slack_ns and ->default_max_slack_ns of the task to fit + * limits of the cgroup. + */ +static void tslack_adjust_task(struct timer_slack_cgroup *tslack_cgroup, + struct task_struct *tsk) +{ + if (tslack_cgroup->min_slack_ns> tsk->timer_slack_ns) + tsk->timer_slack_ns = tslack_cgroup->min_slack_ns; + else if (tslack_cgroup->max_slack_ns< tsk->timer_slack_ns) + tsk->timer_slack_ns = tslack_cgroup->max_slack_ns; + + if (tslack_cgroup->min_slack_ns> tsk->default_timer_slack_ns) + tsk->default_timer_slack_ns = tslack_cgroup->min_slack_ns; + else if (tslack_cgroup->max_slack_ns< tsk->default_timer_slack_ns) + tsk->default_timer_slack_ns = tslack_cgroup->max_slack_ns; +} + +static void tslack_cgroup_attach(struct cgroup_subsys *subsys, + struct cgroup *cgroup, struct cgroup *prev, + struct task_struct *tsk, bool threadgroup) +{ + tslack_adjust_task(cgroup_to_tslack_cgroup(cgroup), tsk); +} + +static int tslack_write_set_slack_ns(struct cgroup *cgroup, struct cftype *cft, + u64 val) +{ + struct timer_slack_cgroup *tslack_cgroup; + struct cgroup_iter it; + struct task_struct *task; + + tslack_cgroup = cgroup_to_tslack_cgroup(cgroup); + if (!val || val< tslack_cgroup->min_slack_ns || + val> tslack_cgroup->max_slack_ns ) + return -EINVAL; + + /* Change timer slack value for all tasks in the cgroup */ + cgroup_iter_start(cgroup,&it); + while ((task = cgroup_iter_next(cgroup,&it))) + task->timer_slack_ns = val; + cgroup_iter_end(cgroup,&it); + + return 0; +} + +static u64 tslack_read_range(struct cgroup *cgroup, struct cftype *cft) +{ + struct timer_slack_cgroup *tslack_cgroup; + + tslack_cgroup = cgroup_to_tslack_cgroup(cgroup); + switch (cft->private) { + case TIMER_SLACK_MIN: + return tslack_cgroup->min_slack_ns; + case TIMER_SLACK_MAX: + return tslack_cgroup->max_slack_ns; + default: + BUG(); + }; +} + +static int tslack_write_range(struct cgroup *cgroup, struct cftype *cft, + u64 val) +{ + struct timer_slack_cgroup *tslack_cgroup; + struct cgroup_iter it; + struct task_struct *task; + + if (!val) + return -EINVAL; + + tslack_cgroup = cgroup_to_tslack_cgroup(cgroup); + switch (cft->private) { + case TIMER_SLACK_MIN: + if (val> tslack_cgroup->max_slack_ns) + return -EINVAL; + tslack_cgroup->min_slack_ns = val; + break; + case TIMER_SLACK_MAX: + if (val< tslack_cgroup->min_slack_ns) + return -EINVAL; + tslack_cgroup->max_slack_ns = val; + break; + default: + BUG(); + } + + /* + * Adjust timer slack value for all tasks in the cgroup to fit + * min-max range. + */ + cgroup_iter_start(cgroup,&it); + while ((task = cgroup_iter_next(cgroup,&it))) + tslack_adjust_task(tslack_cgroup, task); + cgroup_iter_end(cgroup,&it); + + return 0; +} + +static struct cftype files[] = { + { + .name = "set_slack_ns", + .write_u64 = tslack_write_set_slack_ns, + }, + { + .name = "min_slack_ns", + .private = TIMER_SLACK_MIN, + .read_u64 = tslack_read_range, + .write_u64 = tslack_write_range, + }, + { + .name = "max_slack_ns", + .private = TIMER_SLACK_MAX, + .read_u64 = tslack_read_range, + .write_u64 = tslack_write_range, + }, +}; + +static int tslack_cgroup_populate(struct cgroup_subsys *subsys, + struct cgroup *cgroup) +{ + return cgroup_add_files(cgroup, subsys, files, ARRAY_SIZE(files)); +} + +struct cgroup_subsys timer_slack_subsys = { + .name = "timer_slack", + .module = THIS_MODULE, +#ifdef CONFIG_CGROUP_TIMER_SLACK + .subsys_id = timer_slack_subsys_id, +#endif + .create = tslack_cgroup_create, + .destroy = tslack_cgroup_destroy, + .attach = tslack_cgroup_attach, + .populate = tslack_cgroup_populate, +}; + +static int __init init_cgroup_timer_slack(void) +{ + BUG_ON(timer_slack_check != dummy_timer_slack_check); + timer_slack_check = cgroup_timer_slack_check; + return cgroup_load_subsys(&timer_slack_subsys); +} + +static void __exit exit_cgroup_timer_slack(void) +{ + BUG_ON(timer_slack_check != cgroup_timer_slack_check); + timer_slack_check = dummy_timer_slack_check; + cgroup_unload_subsys(&timer_slack_subsys); +} + +module_init(init_cgroup_timer_slack); +module_exit(exit_cgroup_timer_slack); +MODULE_LICENSE("GPL"); diff --git a/kernel/sys.c b/kernel/sys.c index 18da702..57322a7 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -118,6 +118,16 @@ EXPORT_SYMBOL(cad_pid);
void (*pm_power_off_prepare)(void);
+int dummy_timer_slack_check(struct task_struct *task, unsigned long slack_ns) +{ + return 0; +} +EXPORT_SYMBOL_GPL(dummy_timer_slack_check); + +int (*timer_slack_check)(struct task_struct *task, unsigned long slack_ns) = + dummy_timer_slack_check; +EXPORT_SYMBOL_GPL(timer_slack_check); + /* * set the priority of a task * - the caller must hold the RCU read lock @@ -1694,12 +1704,14 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, error = current->timer_slack_ns; break; case PR_SET_TIMERSLACK: - if (arg2<= 0) - current->timer_slack_ns = - current->default_timer_slack_ns; - else - current->timer_slack_ns = arg2; - error = 0; + if (arg2<= 0) { + me->timer_slack_ns = me->default_timer_slack_ns; + break; + } + + error = timer_slack_check(me, arg2); + if (!error) + me->timer_slack_ns = arg2; break; case PR_MCE_KILL: if (arg4 | arg5)